Question: A pole-vaulter is nearly motionless as he clears the bar, set 4.2m above the ground. He then falls onto a thick pad. The top of the pad is 80 cm above the ground, and it compresses by 50cm as he comes to rest.
Part A: What is his acceleration as he comes to rest on the pad?
I need help to solve the above question and express your answer to two significant figures and include the appropriate units.